From German utility model DE 84 34 418 U1 there is known a running gear of a chain block. The running gear includes a U-shaped frame and four wheels adapted to travel on the lower flange of an I-shaped rail. The wheels each have a wheel flange, with which the wheels are guided at the outer side of the lower flange. In the lengthwise direction of the rail, the four wheels are divided into a right pair and a left pair, in the manner of a four-wheeled vehicle. Within the pairs, the two left and the two right wheels are arranged at a distance from one another and one behind the other. Furthermore, one of the two pairs is driven by means of an electric motor. For this, the driven pair of wheels each has a revolving gear rim, arranged in the region of the outer circumference of the wheel flanges. The wheel flanges of the two driven wheels are joined together by a gear arranged between the driven wheels. Thus, this gear meshes with the two wheel flanges of the driven wheels and is fastened on a take-off shaft of a transmission, which is secured to the side of the frame in the lengthwise direction of the rail and, thus, in the direction of travel of the running gear. The frame is thus located between transmission and gear. At the drive end, the electric motor is flanged to the transmission. Furthermore, the frame with the wheels passes around the rail in the manner of a U and has a bolt-shaped cross arm, from which the chain block is hung at the center. The width of the frame can be altered by the cross arm, so that the running gear can be adjusted to the width of different I-shaped rails.
Moreover, from German patent DE 34 18 800 C1 there is known a similar running gear which can travel on the lower flange of an I-shaped rail, especially a suspended rail. This running gear differs essentially from the one previously described in that it has only two wheels with wheel flanges, arranged opposite each other, rather than the four wheels. One of the two wheels is driven by an electric motor with a transmission, which is connected directly to the axle of the driven wheel by its take-off shaft.
From German utility model DE 1 902 712 there is already known a single-rail lower-flange running gear for underhung cranes, including a total of four running wheels arranged one behind the other and opposite each other in the direction of travel. The running wheels are mounted on a right and left side shield, at the inner sides of the side shields. The drive for the running wheels comes from a drive shaft positioned through the side shields at their back side, being connected to an electric motor via the gears of a transmission. The gears of the transmission are enclosed by a housing and thus protected against dirt and grime.